Quantum Physics
Spectral Born machines: classically trainable quantum generative models for discrete data
Austin Huang, William Maxwell, Vasilis Belis et al. (+4 more)
We present spectral Born machines, a class of
quantum generative models that results from viewing and generalizing the class of IQP Born machines through the lens of group
Fourier analysis. These
quantum models exploit the
quantum Fourier transform to create an inductive bias that make them naturally suited to learning integer-structured data, while remaining classically hard to sample from in general. Similar to IQP Born machines, spectral Born machines can be trained efficiently at scale on classical hardware via a maximum mean discrepancy loss based on graph spectral analysis, which we make available in a new tcdq module of the PennyLane software platform. In numerical experiments, we show how the spectral bias of the model leads to significantly reduced parameter counts compared to unstructured approaches, and demonstrate the scalability of the software by training a 190-
qubit model with over 1 million parameters to successfully learn a distribution of 93 nucleotide-long ribosomal RNA. Our results suggest that highly over-parameterized spectral Born machines may be immune to overfitting, even in strongly data-scarce regimes.
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All authors Austin Huang, William Maxwell, Vasilis Belis, Evan Peters, Jason Pye, Soran Jahangiri, Joseph Bowles
Instrumentation and Methods for Astrophysics
Efficient Optimal Image Reconstruction for the Nancy Grace Roman Space Telescope and Beyond: I. First Results with Effortless
Kaili Cao
The forthcoming Nancy Grace Roman Space
Telescope will revolutionize astrophysics by generating huge amounts of data of unprecedented quality. To properly address the data deluge and fully realize its potential, analysis tools that are both efficient and optimal are needed. Effortless (previously known as Fast Imcom) is a new
algorithm for linear image reconstruction. Like its predecessor Imcom, it offers control over point spread functions in output images; by avoiding laborious calculations, it is tens of times faster and has a smaller
memory footprint. In this paper, I apply Effortless to simulated Roman images and present promising first results. With ideal point sources, I illustrate that a single image reconstructed by Effortless, combined with the post-measurement calibration procedure described in a companion paper, can lead to better measurements than a set of $\sim 6$ images coadded by Imcom. While both
algorithms were originally designed for weak gravitational
lensing cosmology, Effortless can benefit studies of static features and dynamic aspects of the Universe alike. Moreover, the efficiency and interpretability of Effortless provides new possibilities for further reducing errors in measurements. The implementation of Effortless is detailed in the companion paper.
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Astrophysics of Galaxies
A redshift of z=3.20 for the bright arc in eMACSJ2229.9-0808: Comment on Wagner & Falco (2026) "Hamilton's Object revisited: A challenging source redshift of a strong lensing configuration"
Ian Smail, Johan Richard, Harald Ebeling et al. (+1 more)
We re-analyse near-infrared and optical spectroscopy from the Subaru, Gemini, and Keck
telescopes of the bright gravitational arc seen in the z=0.62 X-ray cluster eMACSJ2229.9-0808. The 22 strongest spectral features we identify uniquely determine the
redshift of the
galaxy as z=3.20, as previously reported by Ebeling et al. (2025), not z=0.82 as claimed by Wagner & Falco (2026).
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All authors Ian Smail, Johan Richard, Harald Ebeling, A.C. Edge
Quantum Physics
Spin singlets are useful
Silas Hoffman, Edward H. Chen, Matthew Brooks et al. (+6 more)
We evaluate the utility of the
spin-zero
manifold of an exchange-coupled array of $N$
spins for tasks in
quantum computation and
quantum simulation. Since pairs of electrons can be readily initialized into a product state of singlets in semiconducting
quantum dot arrays, the full
spin-zero
manifold is available with exchange-only control, providing a
Hilbert space of approximate dimension $2^N/(N/2)^{3/2}$, asymptotically close to the $2^N$ dimension of the full
spin Hilbert space. Leveraging the
spin-zero
manifold enables larger computational space in a given array compared to traditional exchange-only control, in which
spin arrays are organized into modular units of $n$
spins comprising $N/n$ encoded
qubits, limiting to the exponentially smaller
Hilbert dimension $2^{N/n}$. Here we focus on benchmarking metrics for this resource utilization by generalizing cross-
entropy benchmarking, mirror benchmarking, and out-of-time-ordered correlators to this system. We show that operating in the
spin-zero
manifold can accelerate the realization of computational
quantum advantage applications in
semiconductor-based
spin qubits.
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All authors Silas Hoffman, Edward H. Chen, Matthew Brooks, Stephen Carr, Daniel Volya, Alan Tran, Tyler Keating, Thaddeus D. Ladd, Charles Tahan
High Energy Astrophysical Phenomena
Probing magnetized accretion disk-jet systems: stellar mass to supermassive black holes
Mayank Pathak, Rohan Raha and Banibrata Mukhopadhyay
Ubiquitous nature of
accretion disks and associated jets in modern astrophysics is extreme for black holes. The current state-of-the-art of black hole activities lies with modeling of underlying general relativistic magnetohydrodynamic (GRMHD) flows. These simulations have shown the importance of
magnetic fields in the generation of
outflows/jets and the overall dynamical
evolution of the
accretion flow. They also reveal critical insights into mechanisms that influence
accretion dynamics, jet formation and stability. This further sheds light on the underlying
magnetic field configurations based on
magnetic field saturation leading to Standard and Normal
Evolution: SANE, and Magnetically Arrested Disk: MAD. By employing SKA's high-resolution imaging and sensitivity, we can directly compare simulation outcomes with observational data, validating our models and enhancing our understanding of these phenomena. Key to this investigation is the examination of
magnetic fields and their associated polarization signatures. Comparing the observational data from SKA with GRMHD simulations will facilitate a deeper analysis of the polarization properties, which can reveal the
magnetic field geometry and dynamics in these extreme environments. The VLBI capabilities of SKA will prove instrumental in understanding jet morphologies and spectra of these systems due to its high spatial resolution. Collating these observations with GRMHD simulations will lead to a better understanding of the jet generation mechanisms and their interaction with ambient medium. By integrating advanced GRMHD simulations with SKA's capabilities, we aim to bridge theoretical predictions and observations, ultimately contributing to a more comprehensive understanding of the behavior of accreting black holes and their jets.
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Quantum Physics
Localized Thermometry via Dayem Bridges Integrated on Superconducting Qubit Chips
Ella O. Lachman, Dave P. Pappas, Jayss Marshall et al. (+1 more)
Accurate knowledge of the on-chip temperature is essential for understanding and optimizing the performance of superconducting
qubits, yet direct thermometry at millikelvin temperatures remains challenging. While
qubits themselves are sensitive to the temperature of their environment, other factors may affect the
qubits` effective temperature, and using them as thermometers with any accuracy requires specialized measurement protocols and
qubit designs, limiting their practicality for routine diagnostics and adding complex infrastructure to any hardware testing apparatus. Here we demonstrate a complementary on-chip thermometry method based on superconducting Dayem bridges that are integrated on the same chip as transmon
qubits. By extracting the critical current of the Dayem bridge from I-V measurements, we obtain a local, quantitative measure of the chip temperature without the need for microwave calibration or
qubit-specific control sequences. To demonstrate the utility of the Dayem bridges as thermometers, we fabricate them in-situ with
qubits on the same chip, calibrate the Dayem bridge critical current as a function of temperature, and characterize its resolution and stability at cryogenic temperatures. We additionally perform simultaneous measurements of the Dayem bridge thermometer and
qubit excited-state population, and show agreement over the relevant temperature range, validating the method against established
qubit thermometry. Furthermore, we correlate the independently measured chip temperature with
qubit energy relaxation and dephasing times, demonstrating the utility of this approach for diagnosing temperature-dependent decoherence mechanisms. These results establish integrated Dayem bridges as a simple, non-invasive, and scalable tool for cryogenic hardware development, and on chip thermometry in superconducting
quantum circuits.
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All authors Ella O. Lachman, Dave P. Pappas, Jayss Marshall, Josh Y. Mutus
High Energy Physics (Theory)
Monodromy defects in Chern-Simons theory and Holography
Federico Ambrosino, Jaume Gomis and Suriyah Rajalingam Kannagi
Wilson loop operators in Chern-Simons theory have revealed profound links between
quantum field theory, the fractional
quantum Hall effect,
topology, conformal field theory, and string theory. In Chern-Simons theories with charge conjugation
symmetry, we construct a new class of observables: codimension-two monodromy defects around which fields return to themselves up to charge conjugation. Whereas Wilson loops are labeled by integrable representations of an untwisted affine Lie
algebra, monodromy defects are labeled by those of the corresponding twisted affine
algebra. The modular and fusion data of these two
algebras determine the exact correlation functions of Wilson lines and monodromy defects, which together furnish a $\mathbb{Z}_2$-crossed braided tensor category. The spectrum of line defects in Chern-Simons theory thus gives a physical realization of every
algebra in Kac's classification of affine Lie
algebras: untwisted for Wilson loops, twisted for monodromy defects. We also determine the exact 't Hooft expansion of monodromy defects in $SU(N)_k$ Chern-Simons theory and identify their
holographic duals in topological string theory. The insertion of the lightest monodromy defect has a striking effect: it replaces the resolved conifold background of the Gopakumar-Vafa duality by a specific orientifold of the resolved conifold, transmuting the dual theory of oriented strings into one of unoriented strings. Each excited monodromy defect is then realized as a collection of branes in the orientifold background, with the brane content determined by the representation of the twisted affine
algebra that labels the defect.
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General Relativity and Quantum Cosmology
On the image of the scattering map for horizon-regular solutions of the linear scalar wave equation on the Schwarzschild black hole exterior
Hamed Masaood
We construct
Hilbert-space isomorphisms identifying the spaces of radiation fields on the event horizon and null infinity that are induced by the forward scattering map on the Schwarzschild exterior for fixed spherical harmonic mode solutions to the linear scalar wave equation arising from Cauchy data sets at $t=0$ which are regular at the event horizon, in the sense that the local energy at the event horizon is finite. We show that fixed spherical harmonic mode solutions with no radiation on the event horizon must decay exponentially in time, at a rate that is determined by the surface
gravity. On the other hand, we construct examples of fixed spherical harmonic mode solutions with no radiation on null infinity and which have
polynomial decay along the event horizon. Finally, we construct examples of polynomially decaying solutions to the linear scalar wave equation which are regular at the event horizon, have unbounded support in spherical harmonic modes, and induce no radiation on the event horizon.
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High Energy Physics (Phenomenology)
Anomaly Realization in Charge-Flux Detector Correlators
João Barata, Ratmir Jumanov and Andrey V. Sadofyev
Quantum anomalies provide a bridge between ultraviolet properties of a theory and its infrared sector. We study how this connection appears in axial-charge-flow observables. In the simplest example, an axial-charge detector probes the fermionic cut of the anomalous triangle and resolves its infrared content as an angular distribution. The massless limit does not commute with the angular integration: a contribution suppressed at fixed angle collapses onto the two beam-collinear directions while retaining the finite integrated sum rule fixed by the axial anomaly. We then replace the axial-charge detector by higher-
spin helicity (zilch) detectors and study a family of axial-anomaly-controlled energy-weighted sum rules for the corresponding fluxes. We further show that the same singular localization mechanism and finite zilch-flux sum rules persist in the mixed axial-gravitational channel. We briefly comment on extensions to more general states and multipoint correlators.
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High Energy Physics (Theory)
Effective Field Theories for Material Media
Angelo Esposito, Alberto Nicolis and Riccardo Penco
We review recent progress in understanding certain aspects of condensed matter systems from a high energy theory perspective. We discuss effective field theories that describe collective bulk and localized excitations in a variety of solid and fluid systems. Particular emphasis is placed on the role played by spacetime
symmetries and their spontaneous breaking. The resulting Goldstone dynamics can be seen as underlying a wide variety of phenomena. We attempt to bridge the
language gap between subfields while underscoring the numerous conceptual similarities.
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High Energy Astrophysical Phenomena
Simulating the LOcal Web (SLOW): VII. Intergalactic magnetic field models for multi-messenger applications
Johannes Stoiber, Klaus Dolag, Francesca Capel et al. (+4 more)
Context. The propagation of ultra-high-energy
cosmic rays (UHECRs) and ultra-high-energy gamma-rays remains an open question in astroparticle physics, with the intergalactic
magnetic field (IGMF) playing a crucial role in deflecting charged particles and shaping electromagnetic cascade spectra. Characterizing the IGMF across
cosmic large-scale structure is therefore essential for interpreting multi-messenger observations and constraining the magnetogenesis scenarios that seeded it. Aims. We aim to provide accurate IGMF models to the astroparticle physics community and test their properties and robustness. Methods. We analyze IGMF models derived from the constrained cosmological simulation SLOW alongside a set of rescaled
magnetic field models. We further introduce a novel
algorithm to determine an "ideal position" for
galaxies lying below the constraining power of the initial conditions, enabling accurate line-of-sight
magnetic field extraction toward relevant sources. Results. The models span a wide range of filling factors and sample distinct regions of the electron density-
magnetic field strength phase space in filaments, while converging in the cores of
galaxy clusters; the simulated field from SLOW best reproduces the IGMF derived from the electromagnetic gamma-ray cascade. Models extracted using the introduced "ideal position" yield improved accuracy and may benefit multi-messenger studies more broadly. The large-scale structure drift of simulated clusters exploited by the
algorithm also offers a potential route to refining the simulation's constrained initial conditions.
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All authors Johannes Stoiber, Klaus Dolag, Francesca Capel, Benjamin Seidel, Michael Kachelrieß, Ludwig M. Böss, Jenny G. Sorce
High Energy Astrophysical Phenomena
Effects of Rotation on 3D Core-Collapse Supernova Models for Low-Mass Progenitors
Adam Burrows, Tianshu Wang and David Vartanyan
We explore the dependence upon rotation rate alone of various
supernova observables simulated to their saturation for the explosion of a 9-$M_{\odot}$ progenitor. We find that the explosion energy is non-monotonic with, and weakly dependent upon,
spin across a broad range of initial
spins. The asymmetries of the blast depend weakly on
spin, with faster
spins leading to only slightly greater asymmetries. There is little significant pole-equator
neutrino heating asymmetry during explosion, even for rapid rotation, and only for the fastest rotator does the
neutrino heating rate diminish noticeably. Hence, the effects of rotation alone on all salient aspects of
supernova dynamics are not large. We find that the
recoil kick and
spin are clearly aligned only for the most rapidly rotating model. Interestingly, for the fastest rotator, we witness a $T/|W|$ corotation instabilities near a value of 0.05 and spiral arm modes emerge. We find that the nucleosynthetic yields depend little upon the rotation rate and determine that the ratio of initial to final core
spin period is near $\sim$4000, implying, given the modest inferred
radio pulsar periods at birth, that the initial
spin periods of most
supernova cores are likely quite long. However, we focus on only one progenitor and do not include
magnetic fields. Nevertheless, at least for low-mass progenitors which explode early, we find muted consequences of rotation in most major particulars across a wide range of initial
spins.
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High Energy Physics (Theory)
Generalised global symmetries in 5d $\mathcal{N}=1$ theories from the blow-up equations
William Harding and Noppadol Mekareeya
Five-dimensional $\mathcal{N}=1$ superconformal field theories admit a rich variety of generalised global
symmetries, including higher-form and 2-group
symmetries and their 't$~$Hooft anomalies. We show that this data can be extracted directly from the blow-up equations governing the instanton partition functions of such theories on the $\Omega$-background. The central object is the classical prefactor $\exp(-V_n)$ weighting each
magnetic flux on the blown-up geometry: evaluated on a background for the electric 1-form
symmetry, the fractional parts of its exponents encode the cubic self-anomaly of the 1-form
symmetry and its mixed anomalies with the instanton, flavour, gravitational, and $\mathrm{SU}(2)_R$
symmetries. Combined with the faithful continuous global
symmetry of the ultraviolet fixed point, determined from the superconformal index, the same data decides whether the theory possesses a 2-group
symmetry or a mixed 't$~$Hooft anomaly. We illustrate the method in gauge theories, including $\mathrm{SU}(4)$ and $\mathrm{USp}(4)$ with antisymmetric hypermultiplets and $\mathrm{Spin}(7)$ and $\mathrm{Spin}(8)$ with vector hypermultiplets, as well as in several families of non-Lagrangian theories. New results include the effective prepotentials of the $B_N$ and $B_N^{(1,2,3)}$ families, the cubic 1-form anomalies of the rank-two theories $\mathbb{P}^2\cup\mathbb{F}_3$ and $\mathbb{P}^2\cup\mathbb{F}_6$, and several mixed 1-form–flavour and 1-form–$\mathrm{SU}(2)_R$ anomalies.
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Astrophysics of Galaxies
J-PLUS: Spectral classification and photometric redshifts for 79 million sources in the fourth data release
A. Hernán-Caballero, H. Vázquez Ramió, C. López-Sanjuan et al. (+20 more)
We present spectral classifications and photometric
redshifts for 79.2 million sources up to an r-band magnitude of 22 in Data Release 4 of the Javalambre Photometric Local Universe Survey (J-PLUS). Leveraging the 12-band J-PLUS filter system, we compare a template-fitting approach (LePhare) against LeMoNNADE, a morphology-blind machine learning pipeline that uses spectral mixing augmentation to overcome training set limitations. LeMoNNADE consistently outperforms template fitting in precision, robust scatter, and outlier rates. Including WISE infrared photometry breaks optical degeneracies between
stars and
quasars, reducing the catastrophic outlier rate for
quasars from ~40% to ~23% and constraining systemic
redshift bias to <1% up to z = 4. We find LeMoNNADE is also less susceptible to
redshift aliasing, particularly when adopting the probability density function median. Because the spectroscopic training samples severely under-represent
stars, we apply an Expectation-Maximization
Bayesian calibration to recover unbiased class probabilities for the magnitude-limited sample. This reveals that extragalactic counts agree with the literature down to the r ~ 20.5 completeness limit. The inferred
redshift distribution for r < 21 extragalactic sources peaks at z ~ 0.3, showing broad agreement with existing literature up to z ~ 0.6. The resulting catalogues represent a significant milestone for local Universe science, offering probabilistically calibrated classifications and distances while explicitly characterising faint-end limits and contamination.
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All authors A. Hernán-Caballero, H. Vázquez Ramió, C. López-Sanjuan, D. Muniesa, T. Civera, J. A. Fernández-Ontiveros, H. Domínguez-Sánchez, A. del Pino, J. A. L. Aguerri, S. Zarattini, V. Marra, A. J. Cenarro, D. Cristóbal-Hornillos, C. Hernández-Monteagudo, A. Marín-Franch, M. Moles, J. Varela, J. Alcaniz, R. A. Dupke, A. Ederoclite, L. Sodré Jr., R. E. Angulo, J. Zaragoza-Cardiel
High Energy Physics (Theory)
Perturbiner methods in scattering amplitudes
Renann Lipinski Jusinskas
Berends–Giele currents have recently attracted renewed
attention across the amplitude community, appearing in new contexts ranging from gravitational amplitudes to cosmological correlators and string theory. They can be derived from first principles using the perturbiner method, a thirty-year-old framework that organizes tree-level scattering data in the form of classical multi-particle solutions to field theory equations of motion. After its rediscovery about a decade ago, it has been systematically studied and applied in many different domains. This review aims to provide a pedagogical introduction to the method, covering its basic formulation across a broad but certainly not exhaustive range of models and progressing to some of the most recent findings in the literature. This includes several unpublished results, many of which represent tacit knowledge of the community that has not previously appeared in print.
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Instrumentation and Methods for Astrophysics
A comparison of numerical schemes for driven subsonic MHD turbulence
Rüdiger Pakmor, Thomas Guillet, Rebekka Bieri et al. (+3 more)
Turbulence is ubiquitous in astrophysical systems, and since most
cosmic gas is ionised, it supports
magnetic fields. In turbulent environments, these fields are rapidly amplified through a small-scale dynamo. Multi-scale astrophysical simulations, however, rarely resolve this process adequately. Limited spatial dynamic range makes small-scale amplification sensitive to the numerical choices made in the hydrodynamics and
magnetic field solvers. Here, we investigate idealised periodic boxes of driven subsonic
turbulence with a weak seed
magnetic field. These simulations with purely numerical dissipation provide a simple environment in which an efficient small-scale dynamo is expected. We aim to systematically compare the three widely used magnetohydrodynamics (MHD) codes Arepo, Athena, and Ramses across different divergence-control schemes: constrained transport, Powell cleaning, and Dedner cleaning. To minimise comparison bias, we adopt identical turbulent driving and analysis pipelines across all runs. At sufficient resolution, every code and scheme we test exhibits dynamo-like exponential amplification of the seed field until saturation. The structural properties of the
magnetic field in both the kinematic and saturated regimes are consistent across schemes (with the exception of Arepo's constrained transport) and agree with theoretical expectations. Residual differences, particularly in kinematic amplification rates and saturation strengths at fixed resolution, appear attributable to varying levels of numerical
diffusion. Notably, we find for this setup no systematic advantage of constrained transport over divergence-cleaning methods. We stress that this comparison, conducted in a highly idealised setting, represents a first step. Future extensions to more complex and physically realistic configurations remain essential.
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All authors Rüdiger Pakmor, Thomas Guillet, Rebekka Bieri, Christoph Pfrommer, Volker Springel, Romain Teyssier
Cosmology and Nongalactic Astrophysics
The Treble Clef radio phoenix and its old nonthermal filaments
A. Botteon, M. Brienza, K. Rajpurohit et al. (+15 more)
By inspecting data from the LOFAR Two-meter Sky Survey (LoTSS), we noticed a peculiar bright and filamentary
radio source at low-
galactic latitude ($b \approx 0.5 \deg$). This source, detected also in previous
radio observations, was originally believed to be a
pulsar, but was later suggested to be located in a heavily obscured
galaxy cluster behind the
Galactic plane. In this paper, we characterize for the first time the main properties of the host cluster (
redshift, mass, temperature, X-ray luminosity, and dynamical status) by using X-ray observations performed with Chandra and SRG/eROSITA. In addition, by combining new uGMRT follow-up data with observations from the e LOFAR LBA Sky Survey (LoLSS), we perform a multifrequency, spatially resolved spectral analysis of the filamentary
radio source (VLSS J0318.9+5755, nicknamed here the "Treble Clef" due to its morphology). We conclude that this source is a
radio phoenix belonging to a massive, merging
galaxy cluster in the Zone of Avoidance. We speculate that its complex morphology is shaped by gas motions generated in the intracluster medium during the ongoing merger, which are also likely responsible for the generation of the candidate
radio halo tentatively observed in the cluster center. Owing to its highly filamentary morphology, brightness at $\lesssim$1 GHz, and extremely steep spectrum, reaching values of $\alpha > 4$ between 400 and 650 MHz, this source represents an ideal target for high-resolution, very-low-frequency follow-up observations with LOFAR2.0.
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All authors A. Botteon, M. Brienza, K. Rajpurohit, N. Lyskova, E. Churazov, I. Khabibullin, T. Pasini, E. O'Sullivan, G. Brunetti, F. De Gasperin, E. De Rubeis, F. Gastaldello, D. N. Hoang, R. Kraft, G. Schellenberger, R. Sunyaev, R. J. van Weeren, F. Vazza
High Energy Physics (Phenomenology)
The Positivity Geometry of Photon–Dark-Photon Effective Field Theories
Sayantan Chakraborty, Yash Dadhwal and Arun M. Thalapillil
We derive positivity bounds on the complete dimension-eight effective field theory of
photons and a massless dark
photon. The mixed gauge sector contains twelve CP-even Wilson coefficients and an enlarged helicity-amplitude structure. Using a modified forward-limit dispersion relation, we analytically obtain non-trivial linear and non-linear elastic positivity constraints that define a spectrahedral geometry. We analyze implications of these bounds on non-forward amplitudes and discuss where kinetic-mixing and dark-
axion-portal UV completions populate this geometry.
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High Energy Physics (Theory)
Towards gauge independence in asymptotically safe quantum gravity
Kevin Falls, Renata Ferrero and Giovanni Oglialoro
We study gauge dependence in proper-time renormalisation group flows for asymptotically safe
quantum gravity. Working in an essential scheme, we use field redefinitions to separate redundant off-shell contributions from the on-shell running of physical couplings. We consider two approximations: in the first, we work on general backgrounds and project onto all terms with up to four derivatives, neglecting boundary terms; in the second, we work on a maximally symmetric background and retain all orders in the
Ricci scalar. Although the flow equation depends on the gauge parameters, this dependence can be cancelled order by order once the redundant terms are absorbed by field redefinitions. In the four-derivative approximation, the dependence on the retained gauge parameter drops out of the beta function for Newton's constant to third order in the coupling. On the sphere, the flow becomes independent of both parameters of the general gauge to all
curvature orders, and all orders in the coupling. Crucially, this cancellation depends on the choice of regulator. We verify the mechanism explicitly at one loop, where the gauge-dependent fluctuation contributions are cancelled by the ghost sector on shell. The resulting essential flow displays a gauge-independent non-Gaussian fixed point, supporting the interpretation that universal information in
quantum gravity is encoded in the on-shell essential sector.
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Quantum Physics
Localized control of large ion crystals in a Penning trap using a spatial light modulator
Allison L. Carter, Jennifer F. Lilieholm, Bryce B. Bullock et al. (+3 more)
Penning ion traps as
quantum platforms have primarily utilized global control and symmetric Dicke states for
quantum simulation and sensing experiments. The introduction of local control greatly increases the power of the platform as a
quantum simulator but is technically challenging due to the rapid rotation of the ion
crystals. Here we use an ultraviolet-compatible spatial light modulator (SLM) to imprint programmable AC Stark shift patterns with different azimuthal
symmetries and gradients that co-rotate with the ion
crystals, demonstrating localized coherent control of single plane
crystals with greater than 100 ions. Comparisons of the measured ion
qubit populations with calculations from independent measurements of the applied AC Stark shift patterns show good agreement, validating the technique and providing a path, with a higher format SLM, for parallelizable, coherent individual ion addressing in Penning traps.
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All authors Allison L. Carter, Jennifer F. Lilieholm, Bryce B. Bullock, Kurt Thompson, Diep Nguyen, John J. Bollinger
Instrumentation and Methods for Astrophysics
HDRL Staff Strategy Meeting Report
Brian Thomas, Robert Candey, Jack Ireland et al. (+3 more)
HDRL held its first HDRL wide strategy meeting in January 2026, pulling in a majority of HDRL member staff and selected HDRL grantees. Just over 40 people attended with a few more online to listen to over 30 lightning talks presented by their colleagues and leaders, participate in several breakout and group discussions, and cast 324 votes on over 50 strategic topic ideas contributed by the attendees. The many ideas generated by attendees can be grouped into seven themes which describe the overall breadth of discussion at the meeting. These themes included: Metadata, Standards, and Semantics Discovery, Search, and Recommendation Modernizing HDRL User experience Modernizing HDRL Staff experience Modernized, Scalable, and Dependable Infrastructure for Compute and Storage Metrics and Impact Assessment Community Engagement and Sustainability Considering the gathered information and the interconnections between the prioritized ideas we concluded that several strategic areas for action exist. This document provides an overview of contributed materials and post meeting strategic analysis.
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All authors Brian Thomas, Robert Candey, Jack Ireland, Lan Jian, Rebecca Ringuette, Tressa Helvey-Kalsulke
Materials Science
BatteryMat: a hierarchical machine-learning and DFT framework for average-voltage screening of lithium-ion cathode materials
Jaehyung Lee, Charles Rhys Campbell, Kent Zhang et al. (+1 more)
Density functional theory (DFT) predicts cathode voltages accurately but does not scale to the combinatorial chemical spaces of modern materials databases, while pure machine-learning surrogates are fast but cannot guarantee thermodynamic consistency. We introduce BatteryMat, a three-tier framework that promotes single-pass average-voltage prediction with the Atomistic Line Graph Neural Network (ALIGNN) as the primary screening signal across JARVIS-DFT, then validates survivors with ALIGNN-FF force-field delithiation profiles and automated PBE+U or optB88-vdW+U supercell DFT. The exchange-correlation functional is selected automatically by spacegroup, and the lithium metal reference is recomputed in the same plane-wave basis as the cathode runs, removing a systematic offset of about 1 V present in tabulated values. Trained on 7,610 ALIGNN-FF delithiation voltages, the ALIGNN predictor reproduces the force-field labels with a mean absolute error of 0.17 V and a coefficient of determination of 0.94; this measures
distillation fidelity to the force-field protocol, not agreement with DFT or experiment. On four commercial chemistries (LiFePO4, LiMnPO4, LiMn2O4, LiCoO2) the DFT tier reproduces the experimental average voltage to within 0.3 V and the theoretical volumetric capacity to within 5%; a fifth, non-stoichiometric layered entry is carried as an edge case. The pipeline prioritises, rather than generates, existing structures: it ranks the lithium-containing JARVIS-DFT pool into 71 candidates and a scan of about 4.49 million Alexandria structures into 213, all surrogate-level leads awaiting DFT validation rather than confirmed cathodes. BatteryMat is available at https://github.com/atomgptlab/batterymat with a demo at https://atomgpt.org/battery.
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All authors Jaehyung Lee, Charles Rhys Campbell, Kent Zhang, Kamal Choudhary
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Fingerprint, Not Blueprint: How Positional Schemes Set the Default Spectral Algebra of Attention
Li Hengyu
The pre-softmax score of an
attention head is a bilinear form $score(i,j) = x_i^T M x_j$ in a learned operator $M = W_q^T W_k$. Because M is generally non-symmetric, hence non-normal, it has a complex eigenspectrum and non-orthogonal eigenvectors, the regime where non-Hermitian and random-
matrix tools apply. We ask what this spectrum encodes, at three levels for previous-
token and induction
circuits. Statically, across seven pretrained models spanning three positional schemes, the strongest previous-
token heads are spectrally rotational under RoPE and non-rotational, or content-like, where position enters outside QK (learned-absolute and ALiBi); the model-level separation is perfect at every top-k examined (exact permutation $p=0.029$), and zeroing the per-frequency RoPE phase $Im(M_t)$ eliminates induction on a pre-identified previous-
token head in all three RoPE models. Dynamically, over public Pythia checkpoints every head originates at the random-
matrix (Ginibre) null; the rotational signature emerges with the behavior, not before it, and the population-median suppression that yields the final profile follows
circuit formation, so the profile is a consolidated fingerprint, not a precursor. Causally, and at toy scale, no spectral channel is necessary: constrained two-layer training reroutes around every ban with capability intact, albeit at a significant formation delay (four pre-registered contrasts, $q_BH <= 0.016$). The cost structure exposes each scheme's default: imposing
symmetry slows learned-absolute models by a factor of 2.9, whereas a RoPE head with a fully symmetric static M still routes directionally via the phase channel, impossible under absolute positions. Within the settings examined, the positional scheme sets the default spectral
algebra of an
attention head's solution: a fingerprint sculpted after function, not a hard constraint upon it.
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Instrumentation and Methods for Astrophysics
Fast Graph-based Higher-Order Clustering Statistics on the GPU
Cristiano G. Sabiu
We present a significant update to GRAMSCI (GRAph Made Statistics for Cosmological Information; Sabiu et al. 2019), an
algorithm for the fast computation of the general $N$-point spatial correlation function of any discrete point set. Version 2 adds several features. We replace the binary-search inner loop ($O(m\log m)$ per hub-spoke pair, $m$ being the mean neighbor count) with a merge-walk
algorithm that reduces the inner loop to $O(m)$. We implement a parity-decomposed 4pCF that separates the signal into even and odd channels. We estimate the disconnected 4pCF internally on the same graph to return the connected 4pCF. We add a Python/NumPy interface to the Fortran engine. Principally, we present a GPU port of the full query engine (OpenACC): the 3pCF, 4pCF, and parity-decomposed 4pCF kernels run on a single consumer GPU with measured speedups of $2.6\times$ (3pCF) to $9\times$ (4pCF) over a 64-thread CPU node, and out-of-core tiling handles graphs exceeding device
memory. We measure a $9\times10^9$-edge BAO-scale 3pCF on a 24 GB card with $\sim 20\%$ overhead. We validate the code against its CPU reference, against analytic injection tests, and on exactly solvable random fields (a non-Gaussian multiplicative cascade and a Gaussian field, whose full and connected 4pCF the
estimators reproduce without bias), and demonstrate BAO-scale applications on the DESI DR1 LRG sample (the 3pCF and the full and connected 4pCF over the complete configuration space, both to 150 $h^{-1}$ Mpc).
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Quantum Physics
Real-Time VPN Traffic over ETSI GS QKD 014 Key Delivery with a LuxQuanta NOVA QKD Platform
Felipe Paixão, Anderson Altair Tomkelski, Marcus Elias Silva Freire et al. (+5 more)
This report presents a prototype VPN that uses QKD-derived keys delivered through the ETSI GS QKD 014 API. The VPN encrypts IP traffic with AES-256-GCM, transports ETSI key identifiers in-band, and retrieves matching keys from local KMEs. After validation with a controlled KME simulator, the system was tested on two Jetson Xavier NX devices connected to a LuxQuanta NOVA QKD platform. The experiment successfully transmitted bidirectional real-time audio and
video traffic through the VPN for eight continuous hours, demonstrating the feasibility of integrating classical VPN applications with QKD infrastructure through a standardized key-delivery interface.
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All authors Felipe Paixão, Anderson Altair Tomkelski, Marcus Elias Silva Freire, Isys Nogueira de Sant'Anna, Adriano Humberto de Oliveira Maia, Reinan da Silva Salazar, Ney Ricardo Lopez Junior, João Marcelo Silva Souza
Cosmology and Nongalactic Astrophysics
Skipping the rungs! Calibrating distance indicators through their clustering with galaxies
Madeline L. Cross-Parkin, Leonardo Giani, Cullan Howlett et al. (+1 more)
We show that angular cross-correlations between distance indicators and
galaxy redshift catalogues, when interpreted within an assumed cosmological model, can constrain potential biases in distance measurements induced by calibration systematics. As a test case, we consider a simple scenario in which a constant calibration offset $\Delta M$ shifts all observed distances by a multiplicative factor, and we produce Fisher forecasts for the constraining power on $\Delta M$ and $H_0$ from existing and upcoming surveys. In our most optimistic scenario, based on the expected number of SN Ia observed by LSST and the DESI final data release, we find $\sigma_{\Delta M} \approx 0.05$ and $\sigma_{H_0} \approx 1.81~\mathrm{km~s^{-1}~Mpc^{-1}}$. This has important implications for the Hubble tension, since explaining the discrepancy purely as a calibration systematic in low-$z$ measurements would require $\Delta M \approx 0.13$.
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All authors Madeline L. Cross-Parkin, Leonardo Giani, Cullan Howlett, Tamara M. Davis
High Energy Physics (Theory)
The Chiral Random-Matrix Ensemble of the Type-IIB Axion–Dilaton Wormhole Partition Function
Soo-Jong Rey
I construct a microscopic ADHM/
chiral-Wishart representative of the reduced charge-sector coefficient $W_\nu[b]$ that enters the Type-IIB
axion–dilaton wormhole partition function $Z_{\rm wh}(\theta;b)$. I fix the
axion-charge sector, equivalently the form-field-flux sector, which plays the exact same structural role as a fixed-
topology sector in QCD: it supplies the domain where I compute the microscopic coefficient before forming the final theta sum. At $E=0$, the
axion–dilaton radial family reaches its BPS instanton endpoint. After I impose the
Hamiltonian constraint, gauge quotient, charge-sector boundary condition, and collective zero-mode quotient, the physical quadratic fluctuation operator at that endpoint becomes a positive adjoint square. Its non-zero spectrum is therefore a squared singular-value spectrum, and its microscopic endpoint is a Laguerre/
chiral hard edge. The D(-1)/D3 super-ADHM collective-coordinate integral supplies the Type-IIB microscopic representative of this same coefficient. In the large$N$ result of Dorey et al., this super-ADHM measure becomes the $k$-D-instanton measure on $AdS_5\times S^5$, multiplied by a centered zero-dimensional supersymmetric
matrix-model factor. The
chiral/Wishart ensemble forms the hard-edge limit of the rectangular block inside this super-ADHM integral. Fermionic ADHM variables and supergravity
fermions remain part of the coefficient: in protected sectors they cancel paired non-zero modes, impose zero-mode saturation, and determine which reduction data \(b\) give a non-vanishing $W_\nu[b]$.
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High Energy Astrophysical Phenomena
Minimum Energies and Magnetic Field Strengths of Edge-brightened Compact Symmetric Objects
Tirth D. Surti, Martijn S. S. L. Oei, Anthony C. S. Readhead et al. (+1 more)
Compact symmetric objects (CSOs) are subkiloparsec
radio sources with two-sided emission about a core resulting from jets that are not relativistically beamed towards the observer. This relative simplicity makes them attractive targets to study the launching and
evolution of relativistic jets. We use
radio surveys and spatially resolved VLBA observations to estimate the minimum energies and
magnetic field strengths of a subset of edge-brightened CSOs (CSO-2s). These are necessary to test models of CSO-2 formation via
stellar capture and
evolution via synchrotron cooling. By treating the observed X-ray emission of CSO-2s as inverse Compton emission from synchrotron and external
photon fields, we estimate a mean departure from the minimum energy
magnetic field strengths of ${\sim}2\times$, suggesting that CSO-2 lobes are close to minimum energy. Typical lobal minimum energy
magnetic field strengths of $20$ mG suggest that once the jets shut off, luminous CSO-2s should fade at GHz frequencies within ${\sim}10^{3}$ years. We find that CSO-2 minimum energies are systematically larger than previously estimated. If luminous CSO-2s result from
tidal disruption events, a majority would require the capture of massive
stars $>1 \ M_{\odot}$ assuming jet launching efficiencies less than $100\%$.
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All authors Tirth D. Surti, Martijn S. S. L. Oei, Anthony C. S. Readhead, Andrew G. Sullivan
Mesoscale and Nanoscale Physics
2D Transport in an in-plane magnetic field
Aryaman Babbar and Sankar Das Sarma
A parallel in-plane
magnetic field could, in principle, distinguish between two competing physical scenarios for the experimentally observed density-tuned 2D metal-
insulator transition (where decreasing the carrier density leads to a crossover from an effective metal to an effective
insulator): Wigner crystallization or Anderson localization. Since the main scattering mechanism in 2D doped
semiconductors arises from screened random charged
impurities and screening in turn depends on the electronic density of states, the in-plane
magnetic field could distinguish between the two by decreasing screening through
spin polarization and this enhances the effective critical density for Anderson localization compared with Wigner crystallization. We give the general theory and provide results for the quantitative magnitudes of the
spin polarization effect on the transition density by focusing on two recent experiments [Z. Ge, et al, arXiv:2510.12009, T. Han, et al, arXiv:2604.00113], noting that the critical density may actually decrease if the dominant scattering is by short-ranged defects instead of long-ranged charged
impurities. The difference between the two cases arises from whether
spin polarization dominates screening (enhanced critical density) or the
Fermi surface (suppressed critical density).
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Quantum Physics
Tianhan Liu, Fedor Simkovic IV and Martin Leib
We introduce a
quantum algorithmic framework based on probabilistic mixtures of
unitary channels that, similar to the framework of
quantum singular value transformations, enables the application of arbitrary
polynomials of hermitian operators onto arbitrary initial states. We show that our framework supports a flexible tradeoff between sample- and query complexity ranging from optimal query complexity, meaning logarithmic in the error, and exponentially scaling sample complexity to sub-
polynomial query complexity in the error and
polynomial sample complexity. Combined with the considerably lower
quantum circuit complexity, compared to
quantum singular value transformations with a linear combination of
unitaries block encoding, we argue that our framework can be seamlessly scaled from NISQ to fault-tolerant
quantum computing.
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